#include <iostream>
#include <cstdio>
#include <cmath>
using namespace std;
int main()
{
int n;
scanf("%d",&n);
double m=0.00001;
while(n--){
double a,b,ma;
scanf("%lf%lf",&a,&b);
ma=sqrt(a*a+b*b);
if(ma>m){
m=ma;
}
}
printf("%.2lf",m);
return 0;
}